Pelleted feeds have been successfully utilized in the feeding of fish and animals including monogastric and ruminant animals, fish, shrimp and the like. The advantages of pelleted feeds include: (1) pelleted feeds prevent selective feeding on those ingredients in the formulation which are more palatable and thus more desirable to the animal; (2) pelleting of the feed ration prevents segregation of the various size and density constituents that are inherent in animal feeds; (3) pelleting animal feed results in higher bulk density, which is advantageous for both shipping and handling, resulting in maximum load efficiency and reduced storage requirements; and (4) pelleting also increases nutritional utilization of the feed components, thus increasing conversion rate of the feed formulation.
Generally pelleted feeds are produced in an extrusion type thermoplastic molding operation in which finely divided particles of a feed ration are formed into compact, easily handled pellets. Binder additives may be utilized to improve the strength, durability and stability of the pellets, and to reduce fines produced during the pelleting process. Preferably, nutritive binder additives are utilized which in addition to providing these improvements also provide essential recognized nutrients such as magnesium, calcium, potassium and/or sulfur to the feed.
Pellet stability is particularly important in the production and use of pelleted feeds for fish, shrimp and other water animals. Because shrimp, and other water animals, eat slowly and masticate feed pellets outside their mouth parts, much of the pellet is lost through leaching and fragmentation of the pellet by the water. In addition to representing a waste of feed, the fragmentation and leaching of the pellet contributes to the degradation of the water quality in the feeding pond.
U.S. Pat. No. 4,775,539, the disclosure of which is incorporated by reference, discloses a nutritive teed binder that produces pelleted feeds with improved stability and therefore is advantageous for use in fish and water animal feeds.
Pelleted feeds may also be degraded by high temperatures, e.g. above 100.degree. F., and high humidity, e.g. above 95%. Either of these conditions may cause the pellets to separate and fragment.
Heretofore generally known pellet binders include mixtures of a reactive metal salt and reactive metal hydroxide. When a calcium salt is utilized as the reactive metal salt, or when calcium forms a part of the reactive metal hydroxide, the calcium concentration of the pelleted feed will be increased. Certain species, such as shrimp, may be harmed by feeding on a pelleted feed with a high calcium content, for example greater than about 20%. Similarly, if magnesium forms a part of the metal salt or metal hydroxide, the magnesium concentration of the pelleted feed will be increased. Increased magnesium levels could also prove harmful to certain species. Thus, binders with too great a concentration of calcium or magnesium may prove disadvantageous for certain uses.